This application relates to magnetic disc drives and more particularly to a disc drive having a yielding bend section in an actuator arm suspension.
Disc drives are data storage devices that store digital data in magnetic form on a rotating information storage disc. Modern disc drives comprise one or more rigid information storage discs that are coated with a magnetizable medium and mounted on the hub of a spindle motor for rotation at a constant high speed. Information is stored on the discs in a plurality of concentric circular tracks typically by an array of transducers or xe2x80x9cheadsxe2x80x9d fixed to a slider mounted on a radial actuator arm for movement of the heads in an arc across the surface of the discs.
The actuator arms are driven by an actuator assembly located adjacent to the disc(s) in the disc drive. The actuator assembly includes an E-block that attaches to a plurality of actuator arms. One or more suspensions are attached to the distal end of each actuator arm, where each suspension includes a base-plate for securing the suspension to the actuator arm and a rigid loadbeam for supporting each head of the disc drive above the disc. Suspensions are formed with a bend section that exerts a pre-load force on the head toward the disc.
Each of the concentric tracks is generally divided into a plurality of separately addressable data sectors. The recording transducer, e.g. a magnetoresistive read/write head, is used to transfer data between a desired track and an external environment. During a write operation, data is written onto the disc track and during a read operation the head senses the data previously written on the disc track and transfers the information to a host computing system. The overall capacity of the disc drive to store information is dependent upon the disc drive recording density. It is of particular importance in the disc drive art to maximize the disc drive recording density.
An important parameter affecting the recording density of a disc drive is the spacing between the head and the magnetizable medium layer of the information storage disc. This spacing is known as the head-to-media spacing. Closer head-to-media spacing allows for closer spacing of the magnetic signals, i.e., bits, recorded on the information storage disc which in turn allows for narrower track widths and consequent greater recording densities on the drive. As such, one way to maximize the disc drive recording density is to minimize head-to-media spacing.
However, there are at least two major shortcomings that exist in the art with regard to increasing disc drive recording density by decreasing head-to-media spacing. First, intrinsic spacing variations exist between the head and the magnetizable medium layer of the information storage disc. These variations result from, among other things, part-to-part variations in the pre-load force applied to the head by the suspension structure. Pre-load force variations result from deviations in the suspension geometry, e.g., loadbeam thickness and pre-load bend angle, as well as to the assembly process of the suspension structure and E-block structure. As the head to media space decreases, a point is reached where the spacing variations induced by the suspension pre-load force become as great or greater than the head-to-media spacing itself and it becomes probable that a head will physically contact the surface of the disc. Thus, the intrinsic variations of the head pre-load force places a limit on the degree to which the head-to-media spacing can be reduced.
Second, by increasing the number of tracks on a disc and decreasing the head-to-media spacing, it becomes increasingly important to stably control the head over the track. Stable control of the head is directly affected by the presence of structural resonance within the actuator assembly, and in particular to resonance within the suspension structure of the actuator arm. Resonance within the suspension structure limits the ability of the head to properly operate within the confines of a target track. As the head-to-media spacing decreases with corresponding decreases in track width, resonance within the suspension becomes a correspondingly greater problem. Thus, there is a limit on how small the head-to-media spacing can become that is imposed by resonance within the suspension structure of the actuator arm. Against this backdrop the present invention has been developed.
In accordance with the present invention the above problems and others have been solved by incorporating a suspension into the actuator assembly that has a shortened, stiffer bend section, thereby increasing resonance frequencies of the suspension and allowing for reduced head-to-media spacing.
One embodiment of the present invention is a suspension that connects a slider to an actuator arm. The suspension has a loadbeam anchor sheet for operative attachment to the actuator arm, a bend section, and a loadbeam having a distal end for operative attachment to the slider. The bend section is between and connects the loadbeam anchor sheet to the loadbeam. The bend section is composed of a material that has undergone a stress relief operation while the suspension is attached to the actuator arm.
Another embodiment of the present invention is a method of performing a preload adjustment on a transducer suspension for use in a disc drive. The suspension includes a loadbeam anchor sheet, a bend section, a loadbeam and a slider attached to a distal end of the loadbeam. The method includes attaching the loadbeam anchor sheet of the suspension to an actuator arm of an E-block to form part of an actuator assembly, measuring a pre-load force and z-height of the slider on the suspension on the actuator arm and back bending the suspension until the bend section yields.
These and various other features as well as advantages which characterize the present invention will be apparent from a reading of the following detailed description and a review of the associated drawings.